Shen Dingli is Professor and Executive Dean of the Institute of International Studies at Fudan University, Shanghai.

Recent turbulence on the Korean Peninsula raises several key questions: What is the best way to assure stability? How can the U.S.-ROK alliance play its due role while still being perceived as a stabilizer by other stakeholders? How can China positively interact with the two allies?

If China still feels that the “evidence” that the ROK-led investigation secured regarding the Cheonan’s sinking in March 2010 was not decisive enough to point to Pyongyang, the DPRK’s artillery barrage on Yeonpyeong should have perplexed Beijing. It would certainly be desirable if Seoul could exercise more restraint on its military drills in the waters that the DPRK has claimed, but the North’s shelling of Yeonpyeong is hardly acceptable at all.

There is a rationale that the United States, as the ROK’s staunch ally, would stand firmly in support of its ally. The United States exercised certain restraint in the wake of Cheonan by not sending an aircraft carrier to the West Sea/Yellow Sea. It could not sit idly by not dispatching the USS George Washington after the Yeonpyeong attack, as it would otherwise lose credibility among its allies and send a wrong message to North Korea that its aggressiveness could stand without being properly deterred.

Due to Chinese-U.S. synergy, a second North Korean artillery barrage did not ensue after the ROK’s new round of exercises in December 2010. A number of factors have apparently led to this: the U.S. demonstration of support for its ally, Presidents Hu and Obama’s telephone exchange, and China’s delivery of its firm will not to accept the DPRK’s excessive behavior.

Although China and the United States succeeded in containing adventurism last month, they may still grumble about each other. The United States might suspect that China is an interested party and unable to be impartial, while China’s top brass seems resentful, worrying that the U.S. carrier task force group is approaching China too closely.

Obviously both China and the United States share an interest in stabilizing the situation on the Korean Peninsula and have collaborated at the highest levels to deescalate the confrontation. Nevertheless, China and the United States did not need to hedge against each other while collaborating. As long as stability serves their common interest, they can cooperate to assure that the inter-Korean relationship is managed in a more stable fashion. They could nurture the other’s action by demonstrating leadership in positively shaping the regional security environment.

As for the ROK’s military exercises, it is evident that as a sovereign state, the South is entitled to conduct defensive drills. However, it is crucial that its action is planned and perceived as defensive. In order to avoid being seen as too ambitious, such military exercises ought to be conducted farther from the border area, let alone in an area where sovereignty is disputed.

The South may believe that the waters adjacent to Yeonpyeong are naturally part of South Korea, especially since the UN Command made it so in 1953 and also since the DPRK might have accepted this two decades ago. However, the reality is the DPRK doesn’t accept this at the moment. There exists a dispute now over a past dispute that appeared to be “settled” in the early 1990s. The South may not want the “settled” dispute to be disputed again, but has to respect the new reality and exercise more caution. America, as the ROK’s protector, has a responsibility to both defend its ally and demand it to act very cautiously.

While China has a legal responsibility to protect the DPRK, it also has an obligation to assure its ally not to be aggressive. In fact, China has no responsibility to protect an aggressive “friend”, in which case the ally would not deserve protection as its aggressiveness would automatically free Beijing’s common defense obligation.

If both the United States and China would make their respective treaty rights and obligations crystal clear to the respective Koreas, they would not only follow the UN Charter and reassure their friends, but also forge their own mutual trust. Regrettably this does not seem to be the case. The United States does not appear to have clearly cautioned the ROK, while China appears not to have warned the DPRK of the consequences of provocation or escalation of a crisis which violates their treaty and undercuts China’s national interests.

In the case of Cheonan, even if China may not fully accept the “evidence” that the ROK has presented, there is still a collaborative approach to dealing with the introduction of U.S. naval vessels. It is true that the emergence of USS George Washington in the region did not bode well for China, but one must not forget that the purpose of its participation was not to coerce China in the first place. It was to deter the aggression that led to the Cheonan’s sinking, which coincided with China’s own interests.

It is not inconceivable to turn the Korean Peninsula crisis into an opportunity or to “have both fish and bear’s paw at the same time,” as a Chinese idiom has stated. To prevent China from viewing U.S.-ROK naval drills as provocative, the United States and South Korea could invite China to join. Forging a China-U.S.-ROK-China trilateral naval exercise would carry great political symbolism and expand the international coalition to deter the aggression that has led to recent regional instability.

China may perceive such an invitation as a difficult political choice but less of a security threat. After all, China is the ROK’s “strategic partner” and is building a “positive, cooperative and comprehensive partnership” with America; it is not politically incorrect to work with the two partners for cooperative dissuasion of threats to regional stability. As the DPRK has claimed innocence from the Cheonan incident, there is even less political baggage if China would take this course. Meanwhile, such an invitation would make a U.S.-ROK military move politically less harmful in terms of relations with China, and would grant China some leverage to moderate its partners’ behavior cooperatively.

In sum, there exist better alternatives for dealing with Korean Peninsula securities which are mutually beneficial to all countries involved. Common interests in regional stability could be well served if all players are able to turn the challenges into opportunities. The upcoming Sino-U.S. summit in Washington in January could help develop this sort of wisdom to narrow differences and deepen the space for cooperation.